scholarly journals Sodium hypochlorite pecularities in application for restoration of highly porous fillers after their use in biofiltration systems of recirculating aquaculture systems

2021 ◽  
pp. 23-32
Author(s):  
D. Sharylo ◽  
◽  
V. Kovalenko ◽  
B. Kovalenko ◽  
◽  
...  

Purpose. Development of a method for the regeneration of highly porous fillers for biofilters after slagging of their pores with biofilm residues in the process of growing aquaculture objects in recirculating aquaculture systems (RAS). Methodology. Regeneration of fillers was performed with solutions of sodium hypochlorite of different concentrations (2.5%, 1%, 0.5% of active chlorine) after their exploitation for 6 months. The cleaning efficiency was monitored by the difference in fillers weights after cleaning. Findings. According to the study, the use of sodium hypochlorite for cleaning highly porous fillers for biofilters (using an example of porous ceramic filler and foamed glass «JBL Micromec») is efficient and cost-effective. A reduction in the weight of the test samples averaged 12.95% for porous ceramics and 15.01% for foamed glass. Based on the obtained data, aqueous solutions with different concentrations of sodium hypochlorite do not have a pronounced difference in efficiency, respectively; the optimal for use is a 0.5% solution. Originality. The use of highly porous fillers for biofilters has long been unprofitable in fish farming due to the rapid loss of their main advantages - a high specific area per unit volume as a result of micropore slagging with biofilm residues. As a result, complete regeneration of these filter materials was required annually, which, given the significantly higher cost compared to polymeric fillers, made their use unprofitable. The described technique allows the use of porous ceramics and foamed glass, after their restoration, for a long time, with replacement only after mechanical wear. Practical value. The described method allows using highly porous fillers for biofilters in the process of growing aquaculture objects without their main disadvantage - a rapid decrease in efficiency as a result of pore slagging with biofilm residues. Keywords: RAS, biofilter, filler, restoration, sodium hypochlorite.

2020 ◽  
Vol 67 (1) ◽  
pp. 148-155
Author(s):  
Anatoliy V. Fedotov ◽  
Viktor S. Grigoriev ◽  
Dmitriy A. Kovalev ◽  
Andrey A. Kovalev

To speed up the wastewater treatment under aerobic conditions and to optimize the processes of anaerobic wastewater treatment in digesters, immobilization technologies of microorganisms and enzymes on solid carriers are used. Ceramic carriers based on aluminosilicates and alumina are one of the promising inorganic biomass carriers. (Research purpose) To study the structure of porous ceramic biomass carriers for anaerobic processing of organic waste and evaluate the prospects for their use. (Materials and methods) The substrate for anaerobic digestion was a mixture of sediments of the primary and secondary sewage sumps of the Lyubertsy treatment facilities. K-65 cattle feed was used to ensure the constancy of the composition of organic substances in substrates as a cosubstrate. The authors used the method of low-temperature nitrogen adsorption of Bruner-Emmett-Teller to study the pore structure and specific surface of solid carriers on a specific surface analyzer Quntachrome Autosorb-1. (Results and discussion) The main characteristics (specific surface, volume of micro- and mesopores, predominant pore radius, water absorption and others) of chamotte foam lightweight and highly porous corundum ceramics were determined. It was revealed that ceramic materials with a developed surface and electrically conductive material provided an increase in biogas yield by 3.8-3.9 percent with an increase in methane content by an average of 5 percent. (Conclusions) The results of anaerobic digestion showed a positive effect of both a conductive carrier and highly porous ceramic materials on the process of anaerobic bioconversion of organic waste into biogas. It is advisable to expand experimental studies on the use of a conductive carrier with a developed surface based on highly porous ceramics.


Author(s):  
N. V. Buchilin ◽  
G. Yu. Lyulyukina ◽  
N. M. Varrik

The results of studies of sintering of spinel porous ceramics using aluminum and magnesium oxides as initial components without sintering additives are presented. It is shown that the optimal burning temperature range for the production of materials with an open-cellular porous structure is 1700‒1730 °C. It has been established that the preliminary heat treatment of oxides significantly affects the mechanical characteristics of materials. Materials were obtained with an interconnected porosity of up to 85 % and a compressive strength of up to 1,0 MPa. Ill. 6. Ref. 25.


2021 ◽  
Vol 2 (143) ◽  
pp. 91-102
Author(s):  
Anatoliy V. Fedotov ◽  
◽  
Aleksey S. Dorokhov ◽  
Dmitriy A. Kovalev

As a result of poor quality, parts of tillage equipment have to be replaced 3-7 times a year. One of the reasons is the lack of attention to the possibility of using technical ceramics in agricultural engineering to improve the wear resistance and durability of machine parts. (Research purpose) The research purpose is in assessing the state of research and prospects for the use of ceramic materials in the Russian Federation for the needs of the agro- industrial complex. (Materials and methods) For the experiments has been used nanostructured boehmite obtained by hydrothermal synthesis to improve the properties of materials and coatings. The crack resistance was determined by the indentation method, and the methane content in the biogas was determined by the chromatographic method. (Results and discussion) The article presents the results of the use of aluminum oxide ceramics for the manufacture of parts of tillage equipment, which allows increasing the resource of parts for processing loamy soils by 2.4-4.5 times. The creation of nanocomposites is promising to increase the strength, wear resistance and crack resistance of the material. In the composition of the non-stick coating, the addition of boehmite increases the abrasion strength of the coating and the compressive strength of the samples by 2.2-2.7 times, and improves the quality of casting. The use of highly porous ceramic materials in the gating system helps to reduce waste, reduce production costs, and improve the quality of foundry products. (Conclusions) Ceramic materials due to their high hardness, wear resistance and corrosion resistance are becoming promising for use in the agro-industrial complex. The widespread use of modern ceramic materials as parts of tillage equipment, non-stick coatings and for the filtration of melts will improve the quality of casting, the durability of products, and reduce the cost of their production. Positive results on wastewater treatment with the use of highly porous ceramics allow us to consider it an innovative material for such purposes and it is advisable to continue research in this direction.


2021 ◽  
Vol 340 ◽  
pp. 01048
Author(s):  
Vyacheslav Khusnutdinov ◽  
Artem Ulihin

Highly porous ceramic materials with open porosity are perspective for manufacture of the biosensors. Those materials are used as a framework and open porosity allows to inject a necessary functional components into internal volume. Electroconductive highly porous ceramics on a base of La1-xCaxMnO3 with variable composition have acceptable hardness and relatively low sintering temperature (about 1450°C). In recent work samples of highly porous ceramic with the composition of La1-xCaxMnO3 (x=0.3, 0.5 and 0.7) were obtained by impregnating a carbon nonwoven material with a slip containing pre-synthesized compounds of the desired composition, followed by annealing at 1415-1450îÑ. Obtained materials according to the scanning electron microscopy data have a pore size of up to 100 µm. The conductivity is 0.5-2.5 S/cm.


2021 ◽  
Vol 11 (13) ◽  
pp. 6056
Author(s):  
Egle Rosson ◽  
Acacio Rincón Rincón Romero ◽  
Denis Badocco ◽  
Federico Zorzi ◽  
Paolo Sgarbossa ◽  
...  

Spent fluorescent lamps (SFL) are classified as hazardous materials in the European Waste Catalogue, which includes residues from various hi-tech devices. The most common end-of-life treatment of SFL consists in the recovery of rare earth elements from the phosphor powders, with associated problems in the management of the glass residues, which are usually landfilled. This study involves the manufacturing of porous ceramics from both the coarse glass-rich fraction and the phosphor-enriched fraction of spent fluorescent lamps. These porous materials, realizing the immobilization of Rare Earth Elements (REEs) within a glass matrix, are suggested for application in buildings as thermal and acoustic insulators. The proposed process is characterized by: (i) alkaline activation (2.5 M or 1 M NaOH aqueous solution); (ii) pre-curing at 75 °C; (iii) the addition of a surfactant (Triton X-100) for foaming at high-speed stirring; (iv) curing at 45 °C; (v) viscous flow sintering at 700 °C. All the final porous ceramics present a limited metal leaching and, in particular, the coarse glass fraction activated with 2.5 M NaOH solution leads to materials comparable to commercial glass foams in terms of mechanical properties.


Conservation ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 151-167
Author(s):  
Joseph Tetreault ◽  
Rachel Fogle ◽  
Todd Guerdat

Operation and effluent treatment costs are limiting factors for the success of recirculating aquaculture systems (RAS) in meeting seafood demand in the United States. Adopting a capture-and-reuse waste management model similar to terrestrial agriculture farmers would allow RAS farmers to monetize effluent and offset production costs. The moisture content and nutrient profile of RAS effluent makes it a potential option for use as a hydroponic fertilizer. Treatment of RAS waste is needed to mineralize particulate-bound nutrients before becoming a viable hydroponic nutrient solution. Anaerobic treatment (AT), a method used by municipal and agricultural waste treatment facilities to reduce total solids, has been shown to successfully mineralize particulate-bound nutrients from RAS effluent. Continuously mixed anaerobic batch bioreactors were used to evaluate the degree to which AT may mineralize particulate-bound nutrients in solid RAS waste. Concentrations of twelve different macro- and micro-nutrients were analyzed in the waste before and after treatment. Effluent samples were analyzed to determine the fraction of each nutrient in the solid and aqueous forms. This study showed that AT is an effective method to mineralize particulate-bound nutrients in RAS effluent and the mineralization rate data may be used to design a pilot-scaled flow-through RAS effluent treatment system.


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